Toilet paper

ABSTRACT

To provide a toilet paper that provides an excellent thick feeling, has excellent water-disintegrability, has sufficient softness, provides a security feeling to a human body during use, and is environmentally friendly.The problem is solved by a 3-ply or 4-ply toilet paper, each ply having a basis weight of 10.5 to 12.5 g/m2, containing oxygen-pulped and non-chlorine-bleached softwood kraft pulp in an amount of 50 to 100% by mass of fibers, containing a cationic fatty acid amide-based softener, each ply having a paper thickness of 80 to 100 μm, having a paper thickness of 320 to 400 μm as the entire toilet paper, and having water-disintegrability of 10 seconds or less.

TECHNICAL FIELD

The present invention relates to a toilet paper.

BACKGROUND ART

In a toilet paper, a wiping property may be required when a showertoilet, which is also called a toilet with a washing function, is used(Patent Literature 1 below).

It is desirable that a toilet paper suitable for the shower toilet is amulti-ply product such as a 3-ply or 4-ply product because it is easyfor a consumer to obtain a security feeling during use of thereof.

Incidentally, in a toilet paper, pulp, which is a fiber raw material, isgenerally bleached with a chlorine-based bleaching agent such aschlorine, chlorine dioxide, or sodium hypochlorite in order to increasewhiteness. However, there is also a demand for, for example, anenvironmentally friendly product made from pulp for which thechlorine-based bleaching agent is not used among consumers who placeimportance on a security feeling to a human body and consideration forenvironment.

In addition, a toilet paper is generally manufactured from a fiber rawmaterial obtained by mixing hardwood-derived pulp with a short fiberlength and softwood-derived pulp with a long fiber length. Mainly, atoilet paper containing a large amount of hardwood-derived pulp thateasily improves softness and a surface property is generally used.

CITATION LIST Patent Literature

Patent Literature 1: JP 2011-153387 A

SUMMARY OF INVENTION Technical Problem

However, pulp that has not been bleached with a chlorine-based bleachingagent contains a large amount of remaining lignin, and fibers thereofare hard. For a toilet paper containing this pulp as a main fiber rawmaterial, hardness and surface roughness are easily felt.

Meanwhile, in order for softness to be easily felt, it is known that thestrength of paper is lowered by increasing the blending amount ofhardwood pulp. However, when the blending amount of hardwood pulp isincreased, water-disintegrability easily deteriorates. In particular, ina multi-ply product, water-disintegrability easily deteriorates.Therefore, a multi-ply product having a larger blending amount ofhardwood pulp may be unsuitable for use in a shower toilet.

Furthermore, since hardwood pulp has a short fiber length, paper dust islikely to be generated. Furthermore, when a softener is used, paper dustis more likely to be generated.

Therefore, a main object of the present invention is to provide a toiletpaper that provides a thick feeling that can make a user reassuredduring use thereof in a shower toilet, has sufficient softness, does noteasily generate paper dust, has excellent water-disintegrability, andprovides a security feeling to a human body during use thereof.

Solution to Problem

A first means to solve the above problems is

a 3-ply or 4-ply toilet paper

containing oxygen-pulped and non-chlorine-bleached softwood kraft pulpin an amount of 50 to 100% by mass of fibers, and

a cationic fatty acid amide-based softener,

wherein each ply has a basis weight of 10.5 to 12.5 g/m² and a paperthickness of 80 to 100 μm, and

the toilet paper has an overall paper thickness of 320 to 400 μm andwater-disintegrability of 10 seconds or less.

Advantageous Effects of Invention

The above present invention provides a toilet paper that provides athick feeling that can make a user reassured during use thereof in ashower toilet, has sufficient softness, does not easily generate paperdust, has excellent water-disintegrability, and provides a securityfeeling to a human body during use thereof.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of an embossment according to an embodiment of thepresent invention.

FIG. 2 is a schematic view for explaining a procedure for measuring thedepth of the embossment according to the present invention.

FIG. 3 is a perspective view of a toilet roll according to an embodimentof the present invention.

DESCRIPTION OF EMBODIMENTS

A toilet paper according to the present embodiment is a 3-ply or 4-plyproduct. That is, the toilet paper according to the present embodimenthas three or four sheets stacked. When the toilet paper is a product ofmulti-ply exceeding 2-ply, such as a 3-ply or 4-ply product, the paperthickness of the entire paper is large while each ply is thin, and thepaper can be hardly torn and can provide a security feeling whileparticularly “softness” is easily felt.

Note that a 2-ply product hardly exhibits a thick feeling, and is likelyto provide a poor security feeling when the paper absorbs a large amountof water and wipes the water after use in a shower toilet. In addition,when the toilet paper is a 5 or more-ply product, even if each ply isthin, softness is hardly felt when the skin is wiped with the toiletpaper. In addition, when a 5 or more-ply product is used at the basisweight and the paper thickness per ply according to the presentinvention described later, and particularly an embossment is imparted tothe toilet paper, strong rigidity is felt, and softness is hardly felt.

On the other hand, in the toilet paper according to the presentembodiment, the basis weight of each ply is 10.5 g/m² or more and 12.5g/m² or less. The basis weight of each ply is preferably 10.6 g/m² ormore and less than 12.4 g/m², and more preferably 10.7 g/m² or more and12.3 g/m² or less. If the basis weight of each ply is within this range,sufficient difficulty in tearing and favorable touch can be obtainedwhen the above 3-ply or 4-ply product is used. In addition,water-disintegrability is easily exhibited. Note that the basis weightaccording to the present invention is measured by the basis weightmeasuring method of JIS P 8124 (1998).

On the other hand, the toilet paper according to the present inventionneeds to be made from softwood kraft pulp in which constituent mainfibers, that is, 50% by mass or more of the constituent fibers areoxygen-pulped and non-chlorine-bleached. The toilet paper according tothe present invention is preferably made from softwood kraft pulp inwhich 80% by mass or more the constituent fibers are oxygen-pulped andnon-chlorine-bleached, and particularly preferably softwood kraft pulpin which substantially 100% by mass of the constituent fibers withoutconsidering impurities and the like are oxygen-pulped andnon-chlorine-bleached. More specifically, this softwood kraft pulp isalso called NOKP, and is manufactured by continuously oxygen-pulpingfibers in a continuous pulping pot, and particularly is not bleachedwith a chlorine-based bleaching agent thereafter. Here, kraft pulp (KP)used for a toilet paper includes a bleached one and an unbleached one,and an unbleached one contains a large amount of lignin. The softwoodkraft pulp according to the present invention has not been bleached witha chlorine-based bleaching agent, but has been oxygen-pulped(oxygen-delignified). Therefore, about half of the content of lignin hasbeen removed from the softwood kraft pulp. Note that the chlorine-basedbleaching agent means not only chlorine but also chlorine dioxide andsodium hypochlorite. Therefore, ECF pulp is not the above softwood kraftpulp according to the present invention.

The toilet paper according to the present invention contains 50% by massor more, preferably 80 to 100% by mass or more of softwood kraft pulpthat has not been bleached with a chlorine-based bleaching agent but hasbeen delignified by oxygen-pulping. In other words, the toilet paper ismanufactured by using the softwood kraft pulp as a main fiber rawmaterial, particularly as a whole fiber raw material. Therefore, thetoilet paper provides a security feeling to a human body during use, andis environmentally friendly. Note that particularly a toilet papercontaining 50% by mass or more of the softwood kraft pulp is lightbrown, is likely to give a visual impression of a natural product thathas not been chemically treated, and gives a soft impression. Therefore,the toilet paper provides a large security feeling to a purchaserthereof.

Meanwhile, since the content of lignin has been reduced to about half ofthat before oxygen-pulping by the delignification treatment byoxygen-pulping. Therefore, the toilet paper exhibits softness moreeasily than a toilet paper containing pulp that has not been delignifiedat all as a raw material, and easily acquires a sufficient strength. Inaddition, the content of hardwood kraft pulp that is likely to reducewater-disintegrability can be at least less than 50% by mass, andparticularly 0% by mass. The toilet paper easily exhibits favorablewater-disintegrability, and hardly generates paper dust.

In addition, since lignin is not hydrophilic, softwood kraft pulp thatcontains lignin and has been oxygen-pulped and non-chlorine-bleached hasa low fiber swelling property and a weak interfiber bond. Therefore,fibers are sparse, and water-disintegrability is favorable. Furthermore,softwood kraft pulp is derived from softwood, and therefore has a longerfiber length than hardwood-derived pulp. Therefore, softwood kraft pulphardly generates paper dust, and has an excellent cushioning property incombination with lignin's action of preventing fibers from being dense.

A fiber component other than oxygen-pulped and non-chlorine-bleachedsoftwood kraft pulp is not necessarily limited. However, it is desirablethat oxygen-pulped and non-chlorine-bleached hardwood kraft pulp is usedbecause the oxygen-pulped and non-chlorine-bleached hardwood kraft pulphas a light brown appearance and provides a security feeling thatbleaching with a chlorine-based bleaching agent has not been performed.Virgin pulp or used paper pulp other than the oxygen-pulped andnon-chlorine-bleached hardwood kraft pulp may be used. In a step ofregenerating pulp from used paper, fibers in used paper pulp tend to befiner than pulp fibers before regeneration, and due to such a nature ofthe fibers, the fibers easily become dense without increasing a paperthickness, and paper strength easily increases. Meanwhile, if anexcessive amount of used paper pulp is blended, texture such asflexibility is reduced. Therefore, in consideration of thecharacteristics of used paper pulp, the blending ratio thereof onlyneeds to be set within a range of 0 to less than 20% by mass. Note thatthe type of used paper pulp is not necessarily limited. Used paper pulpmade from milk carton used paper or high-quality used paper can be used.

The toilet paper according to the present invention can be a toiletpaper that provides an excellent thick feeling, has excellentwater-disintegrability, has sufficient softness, hardly generates paperdust, provides a security feeling to a human body during use, and isenvironmentally friendly by containing 50 to 100% by mass ofoxygen-pulped and non-chlorine-bleached softwood kraft pulp, having abasis weight of 10.5 to 12.5 g/m² per ply, and being formed into amulti-ply product such as a 3-ply or 4-ply product.

On the other hand, it is desirable that the toilet paper according tothe present invention is a non-moisturizer-applied paper to which amoisturizer has not been externally applied substantially. Themoisturizer as an external additive according to the present inventionis a polyol, examples of which include at least glycerin, diglycerin,propylene glycol, 1,3-butylene glycol, and polyethylene glycol. However,inclusion of the above component is not denied as long as the content ofthe above component is so small that an influence thereof is at a levelnot being worthy of a moisturizing toilet paper. The toilet paperaccording to the present invention provides an excellent securityfeeling to a human body. When a moisturizer is applied to the toiletpaper, stickiness and moist feeling peculiar to the moisturizer arefelt, and therefore the above security feeling to a human body isreduced.

On the other hand, the toilet paper according to the present inventioncontains a softener that determines softness and paper strength of abase paper itself, the softener being internally added duringpapermaking. The softener contained in the toilet paper according to thepresent invention is a cationic fatty acid amide-based softener. Thecationic fatty acid amide-based softener does not reduce an effect dueto inclusion of lignin, and acts to coat surfaces of the fibers. Even ifthe toilet paper contains a large amount of pulp containing lignin, thetoilet paper has a smooth surface, remarkably reduces a stiff feeling,and enhances a fullness. As a specific example of the cationic fattyacid amide-based softener, it is desirable that the cationic fatty acidamide-based softener is a reaction product between an amide-basedcompound obtained by a reaction between a polyalkylene polyamine and amonocarboxylic acid, and epihalohydrin. An effect is exhibited if thiscationic fatty acid amide-based softener is used. Note that when thereaction product between an amide-based compound obtained by a reactionbetween a polyalkylene polyamine and a monocarboxylic acid, andepihalohydrin is internally added, the product is preferably mixed withan emulsifier having an alkyl group and/or an alkenyl group having 4 to20 carbon atoms, and water and added. The content of the cationic fattyacid amide-based softener is not necessarily limited. However, when afixing ratio is 50 to 60%, the amount thereof added during manufacturingonly needs to be 0.5 to 4.0 kg/pulp t.

Furthermore, it is desirable that a softening moisturizer is internallyadded to the toilet paper according to the present invention. It isdesirable that the content thereof is 0.2 to 2.0 kg/pulp t. By inclusionof the softening moisturizer, suppleness is improved. A particularlypreferable softening moisturizer is a reaction product obtained bycausing a compound obtained by adding an alkylene oxide having 2 to 4carbon atoms to active hydrogen of a polyalkyleneimine having a weightaverage molecular weight of 500 to 10,000 to react with a higher fattyacid having 12 to 24 carbon atoms and/or an ester compound of a higherfatty acid having 12 to 24 carbon atoms. By inclusion of this softeningmoisturizer, softness is further improved.

In the toilet paper according to the present invention, each ply has apaper thickness of 80 to 100 μm, and the toilet paper has an overallpaper thickness of 320 to 400 μm. When the paper thicknesses of each plyand the toilet paper are within this range, an excellent fullness,excellent softness, and a reassuring thick feeling can be provided. Thepaper thickness of the toilet paper is obtained by sufficiently (usuallyfor about eight hours) subjecting a test piece to humidity control underconditions of JIS P 8111 (1998), and then measuring the paper thicknessin a 1-ply state using a dial thickness gauge (thickness measuringinstrument) “PEACOCK G type” (manufactured by Ozaki MFG. Co. Ltd.) underthe same conditions. Specifically, it is confirmed that there is norubbish, dust, or the like between a plunger and a measuring table, theplunger is placed on the measuring table, a scale of the dial thicknessgauge is moved to adjust a zero point, then the plunger is raised, asample is placed on a test table, the plunger is lowered slowly, and thecurrent gauge is read. When the toilet paper is embossed, measurement isperformed such that one constituent concave (convex) is necessarilywithin a range of the measuring table. Note that when there are concaveswith different depths, measurement is performed such that the deepestconcave is located within the range of the measuring table. During thismeasurement, the plunger is only placed and not pressed. A terminal ofthe plunger is made of metal, and a circular plane thereof with adiameter of 10 mm strikes perpendicularly to a paper plane, and a loadis about 70 gf when the paper thickness is measured. Note that the paperthickness is an average of values obtained by performing the measurement10 times. Here, when the paper thickness is measured, crushing of anembossment (concave) is assumed, but the paper thickness according tothe present invention is a value measured including such crushing, andsuch crushing may be ignored. In the present paper thicknessmeasurement, a difference in paper thickness caused by crushing of aconcave can be ignored.

It is desirable that the toilet paper according to the present inventioncontains pulp fibers that is not unbeaten. It is desirable that thebeating degree of a papermaking raw material during manufacturing is notnecessarily limited, but it is desirable to beat the papermaking rawmaterial such that a down width of the Canadian standard freeness is 20cc to 50 cc. This down width is much smaller than the beating width of ageneral papermaking raw material. In this case, the Canadian standardfreeness of the papermaking raw material is approximately 600 cc ormore. By preventing the pulp fibers from being beaten too much andpreventing the pulp fibers from being unbeaten in this way, the softeneris easily fixed to surfaces of the fibers when the softener isinternally added so as to be contained, and the fibers are moderatelyentangled with each other. A small desired paper thickness is easilyobtained, excellent softness is achieved, and a favorable fullness isprovided. Moreover, paper dust is extremely unlikely to be generated.The paper thickness can be further adjusted with a crepe ratio.

The toilet paper according to the present invention may be embossed. Anemboss pattern thereof is not necessarily limited. An embossment can bean appropriate emboss pattern such as a micro-embossment, a dot-shapedembossment, or a design embossment. However, it is desirable that theemboss pattern according to the present invention is imparted in a plystacked state called a single embossment.

A suitable emboss pattern according to the present invention has aconcave area of 1.0 to 2.5 mm², a density of 5.0 to 50 pieces/cm², andan embossment depth of 0.05 to 0.5 mm. Softness of the toilet paper isimproved, and softness in a rolled state like a toilet roll isincreased, which makes a consumer easily feel that the toilet paper issoft when the consumer holds the toilet paper in his/her hand. Inparticular, as illustrated in FIG. 1, on the entire surface of paper,square concaves 31 (FIG. 1A) in each of which a bottom surface isdiagonal L4×diagonal L4=1.0 to 1.5×1.0 to 1.5 mm or substantially squareconcaves 32 (FIG. 1B) obtained by extending corners of the squaresdiagonally outward are arranged in a lattice with a center spacing L5 of4.5 to 5.5 mm and an arrangement angle of 45° with respect to a widthdirection, and there is a valley line portion 33 extending from each ofthe corners of the concave between the concave 31 (32) and the concave31 (32). Note that it is desirable that the valley line portion 33 isgradually gently formed in a cross-sectional arch such that the valleyline portion 33 is deepest in the corners of the concave 31 (32) andshallowest in the middle between the concaves. This emboss pattern isexcellent in softness and a stool wiping property.

The depth of embossing is measured by a one-shot 3D measurementmacroscope VR-3200 manufactured by KEYENCE CORPORATION or its equivalentmachine, and image analysis software “VR-H1A” or its equivalentsoftware. Measurement is performed under conditions of a magnificationof 12 times and a visual field area of 24 mm×18 mm. However, themagnification and the visual field area can be appropriately changeddepending on the size of an embossment (concave). A specific measurementprocedure will be described with reference to FIG. 2. Using the abovesoftware, an embossment depth (measurement cross-sectional curve)profile at a line segment Q1 crossing the longest portion of aperipheral edge of one embossment (concave) 40 in an image portion (Xportion in the drawing) illustrated by a plane viewpoint is obtained. A“contour curve Q2” of an image portion (Y portion in the drawing)illustrated by a cross-sectional viewpoint is obtained by removing acomponent of surface roughness having a shorter wavelength than Ac: 800μm (provided that Ac is the “filter that defines a boundary between aroughness component and a waviness component” described in JIS-B0601“3.1.1.2”) from the cross-sectional curve of this embossment depthprofile with a low pass filter. In this contour curve Q2, a minimumvalue sandwiched between two concave edge points P1 and P2 that areprotruding upward and have the strongest bend and concave edge points P1and P2 is determined and defined as a minimum depth value Min.Furthermore, an average value of the depth values of the concave edgepoints P1 and P2 is defined as a maximum depth value Max. In this way,embossment depth=maximum value Max−minimum value Min. In addition, adistance (length) between the concave edge points P1 and P2 on the X-Yplane is defined as the length of the longest portion. The above twoconcave edge points P1 and P2 that are protruding upward and have thestrongest bend are visually selected. Note that for the selection, acontour E in the image illustrated by a plane viewpoint of theembossment (concave) 40 during the measurement may be referred to.Similarly, the depth of an embossment (concave) is measured for theshortest portion in a direction perpendicular to the longest portion,and a larger value is adopted as the depth of the embossment (concave).The above measurement is performed for any 10 embossments on a surfaceof the toilet paper, and an average value thereof is defined as a finalembossment depth.

Note that also for the area of each concave of the emboss pattern, acontour of an embossment concave is visually confirmed from a 3D imageobtained by measurement with a one-shot 3D measurement macroscopeVR-3200 or its equivalent machine and image analysis software “VR-H1A”or its equivalent software, and an area inside the contour is measured.The above measurement is performed for any 10 embossments on a surfaceof the toilet paper, and an average value thereof is defined as a finalarea of the embossment concave.

The toilet paper according to the present invention haswater-disintegrability of 10 seconds or less, which is very fast. Thisis because 50% by mass or more, preferably 80% by mass or more,particularly 100% by mass of the constituent fibers is softwood kraftpulp containing lignin, and the fibers are easily loosened. Ifwater-disintegrability is within 10 seconds, a risk of clogging a pipeis remarkably reduced when the toilet paper is discarded into runningwater in a flush toilet or the like. This water-disintegrability(easiness of loosening) is measured according to JIS P 4501 (1993). In atest for easiness of loosening, a 300 mL beaker containing 300 mL ofwater (water temperature 20±5° C.) is placed on a magnetic stirrer, andthe rotation speed of a rotor is adjusted to 600±10 revolutions/minute.A test piece of a 100±2 mm square is put into the beaker, and astopwatch is pressed. The rotation speed of the rotor once drops toabout 500 revolutions due to a resistance of the test piece, and risesas the test piece is loosened. When this rotation speed recovers to 540revolutions, the stopwatch is stopped, and the time is measured in unitsof one second. A result of easiness of loosening is expressed by anaverage of results of five tests. The rotor has a disk shape having adiameter of 35 mm and a thickness of 12 mm.

It is desirable that the toilet paper according to the present inventionhas a longitudinal dry tensile strength of 500 cN/25 mm or more and 1200cN/25 mm or less, more preferably 600 cN/25 mm or more and 1000 cN/25 mmor less. It is desirable that the toilet paper according to the presentinvention has a lateral dry tensile strength of 200 cN/25 mm or more and450 cN/25 mm or less, more preferably 200 cN/25 mm or more and 350 cN/25mm or less. If the dry tensile strength is within this range, the toiletpaper is sufficiently durable for use.

Note that the longitudinal direction of paper is also referred to as MD(Machine Direction) and is a flow direction during papermaking. Thelateral direction of paper is also referred to as CD (Cross Direction),and is a direction perpendicular to a flow direction (MD) duringpapermaking. The dry tensile strength according to the present inventionis a value measured based on JIS P 8113 (2006), and is measured asfollows. As a test piece, a tissue paper cut into a size of about 25 mm(±0.5 mm) (width)×about 150 mm (length) in both MD and CD is used. Thetest piece is measured in a state of multiple plies. As a tester, a loadcell tensile tester TG-200N manufactured by Minebea Co., Ltd. and itsequivalent machine are used. Note that a grip interval is set to 100 mm,and a tensile speed is set to 100 mm/min. The measurement is performedby tightening both ends of the test piece to a grip of the tester,applying a tensile load to the paper piece in an up-down direction, andreading an indicated value (a digital value when the value is indicatedby the digital value) when the paper breaks. Five sets of samples areprepared in each of MD and CD, and each sample is measured five times.An average of the measured values is defined as a dry tensile strengthin each of the directions.

It is desirable that the toilet paper according to the present inventionhas a wet tensile strength in MD of 50 cN/25 mm or more and 100 cN/25 mmor less. It is desirable that the toilet paper according to the presentinvention has a wet tensile strength in CD of 15 cN/25 mm or more and 70cN/25 mm or less. The wet tensile strength is a value measured based onJIS P 8135 (1998), and is measured as follows. As a test piece, a tissuepaper cut into a size of about 25 mm (±0.5 mm) (width)×about 150 mm(length) in both MD and CD is used. A multi-ply tissue paper is measuredin a state of multiple plies. As a tester, a load cell tensile testerTG-200N manufactured by Minebea Co., Ltd. and its equivalent machine areused. Note that a grip interval is set to 100 mm, and a tensile speed isset to 50 mm/min. The test piece used has been cured for 10 minutes in adryer at 105° C. The measurement is performed by tightening both ends ofthe test piece to a grip of the tester, then horizontally impartingwater to a central portion of the test piece with a width of about 10 mmusing a flat brush containing water, immediately thereafter applying atensile load to the paper piece in an up-down direction, and reading anindicated value (digital value) when the paper breaks. Five sets ofsamples are prepared in each of MD and CD, and each sample is measuredfive times. An average of the measured values is defined as a wettensile strength in each of the directions. Wet tensile strength wasalso measured in a stack of a plurality of sheets according to thenumber of plies of a product.

It is desirable that the toilet paper according to the present inventionhas an MMD value of 7.5 or more and 11.0 or less, which is an indicatorindicating a surface property. When the MMD is less than 7.5, thesurface is too smooth, and a wiping property deteriorates. When the MMDexceeds 11.0, the toilet paper may have poor touch and may be unsuitablefor use as a toilet paper. Note that in measuring MMD, while a contactsurface of a friction element is brought into contact with a surface ofa measurement sample to which a tension of 20 g/cm is applied in apredetermined direction at a contact pressure of 25 g, the measurementsample is moved by 2 cm in substantially the same direction as thedirection in which the tension is applied at a speed of 0.1 cm/s, and afriction coefficient at this time is measured using a friction sensetester KES-SE (manufactured by Kato Tech Co., Ltd.) or its equivalentmachine. A value obtained by dividing the friction coefficient by afriction distance (moving distance=2 cm) is MMD. The friction element isformed by adjoining 20 piano wires P each having a diameter of 0.5 mm,and has a contact surface formed such that the length and the width areboth 10 mm. On the contact surface, a unit bulging portion having a tipformed with 20 piano wires P (radius of curvature: 0.25 mm) is formed.

It is desirable that the toilet paper of the present embodiment hasSoftness of 2.0 cN/100 mm or more and 3.5 cN/100 mm or less. Softness isone of indicators of softness, in which paper is softer as the paper hasa lower value of Softness. A tissue paper or a toilet paper havingSoftness of 3.5 cN/100 mm or less is evaluated to be soft. Softness is avalue measured based on a handle-o-meter method according to the JIS L1096 E method (1990). However, a test piece has a size of 100 mm×100 mm,and a clearance is set to 5 mm. A 1-ply product is measured five timesin each of MD and CD, and an average of the total 10 values is definedas Softness. Softness is unitless, but may be expressed in units ofcN/100 mm considering the size of a test piece.

In the toilet paper according to the present embodiment, the dry tensilestrength and the wet tensile strength can be adjusted without using apaper strength agent such as a dry paper strength enhancer or a wetpaper strength enhancer. In particular, it is desirable that the toiletpaper contains no paper strength agent from a viewpoint of a user'ssecurity feeling. By blending a large amount (80% by mass or more,particularly 100% by mass) of softwood kraft pulp having a long fiberlength in the toilet paper according to the present invention,entanglement between the fibers is ensured, and sufficient strength foruse can be achieved even if the toilet paper contains no paper strengthagent. Moreover, the toilet paper contains lignin, and therefore alsohas excellent water-disintegrability. That is, sufficient strength canbe ensured without using a paper strength agent, and excellentwater-disintegrability can be further achieved.

Note that it is desirable that the toilet paper of the presentembodiment does not use a dry paper strength enhancer or a wet paperstrength enhancer as described above, but the toilet paper may use thedry paper strength enhancer or the wet paper strength enhancer asnecessary as long as water-disintegrability is not impaired. Examples ofthe dry paper strength enhancer here include starch, polyacrylamide, andcarboxymethyl cellulose (CMC) or salt thereof such as sodiumcarboxymethyl cellulose, calcium carboxymethyl cellulose and zinccarboxymethyl cellulose.

Examples of the wet paper strength enhancer include a polyamidepolyamine epichlorohydrin resin, a urea resin, an acid colloid/melamineresin, heat-crosslinkable coating PAM, TS-20 manufactured by Seiko PMCCorporation, a polymer aldehyde-functional compound such as glioxylatedpolyacrylamide and cationic glioxylated polyacrylamide, a copolymer ofan acrylamide monomer modified with a divalent aldehyde of glyoxal andanother copolymerizable unsaturated monomer, and dialdehyde starch.

On the other hand, the toilet paper of the present embodiment may have asheet-like shape. However, as illustrated in FIG. 3, the toilet paper issuitably in a form of a toilet roll obtained by winding a belt-shapedtoilet paper 10 around a paper tube (also referred to as a tube core) 20into a roll shape.

It is desirable that the toilet roll according to the present inventionhas a winding diameter L2 (diameter) of 110 to 115 mm. The windingdiameter of the toilet roll is defined as 120 mm or less in JIS P 4501,and a holder for setting a general toilet roll is created based on this120 mm. The toilet roll of the present invention has a winding diameterof 110 to 115 mm, and has a size that can be sufficiently set in ageneral holder. Here, the winding diameter is a value measured using adiameter rule manufactured by Muratec KDS Corporation or its equivalentmachine. An average of measured values at three different locations in awidth direction is used as a measured value. Note that an average valuefor five rolls is used as an average value for products in the samemanufacturing lot.

Meanwhile, it is desirable that the toilet roll has a winding length of20 to 40 m and a winding density of 0.20 to 0.30 m/cm² at this time. Thewinding density here is a value calculated by winding length (m)/actualcross-sectional area. The actual cross-sectional area is a valuecalculated by {(winding diameter/2)×(winding diameter/2)×π−(paper tubeouter diameter/2)×(paper tube outer diameter/2)×π} (unit: cm²). That is,the actual cross-sectional area is an area obtained by subtracting thearea of the paper tube on an opening end side from the area of an endsurface. In the above roll form, when the toilet paper according to thepresent invention has a winding density of 0.20 to 0.28 m/cm², softnessis remarkably felt when the roll is held in the hand on a peripheralsurface thereof. Note it is desirable that a paper tube outer diameter(paper tube diameter) L3 is 35 to 45 mmφ, which is similar to a generalsize.

It is desirable that the toilet paper of the present invention has aroll winding tightness of 1.8 to 3.0 mm. A “handy compression testerKES-G5” manufactured by Kato Tech Co., Ltd. is used to measure the rollwinding tightness (mm) (T0-TM). A toilet roll TR is placed horizontallyon a horizontal pedestal made of a steel plate such that a central axisof the toilet roll TR is horizontal. A steel plate terminal having acircular plane with a compression area of 2 cm² is brought into contactwith the center of an upper surface of an outer periphery of a rolltrunk. With this contacted state as a zero point, the steel plateterminal is moved vertically downward at a speed of 10 mm/min from thezero point to compress the toilet roll. (T0-TM) (mm) is defined as aroll winding tightness (mm), in which T0 (mm) represents the amount ofpushing when a compression load is 0.5 gf/cm², and TM (mm) representsthe amount of pushing when the compression load is 50 gf/cm². The largerthe roll winding tightness (mm), the larger a pushing depth at the timeof pushing at a maximum load of 50 gf/cm², which indicates that thepaper is fluffy. That is, this corresponds to a fullness. Note that theabove winding length and winding density can sufficiently provide thewinding tightness.

Furthermore, it is desirable that the toilet roll of the presentinvention has a compression work amount (WC) of 3.5 to 5.5 gf·cm/cm².The compression work amount (WC) is a work amount from a time point whena steel plate terminal is brought into contact with a roll at 0.5 gf/cm²to a time point of pushing at a maximum load of 50 gf/cm². The largerthe compression work amount (WC), the weaker a repulsive force at aninitial stage of pushing. Therefore, at a moment when the roll isgrabbed, the roll is felt to be soft. Thereafter, when the compressionload is raised to 50 gf/cm² at which the roll is usually grabbed, theroll can be evaluated to be soft and fluffy.

The toilet paper according to the present invention containsoxygen-pulped and non-chlorine-bleached softwood kraft pulp containinglignin and having a long fiber length in an amount of 50% by mass ormore of fibers, in which a bond between the fibers is moderately weak.Therefore, when the toilet paper is formed into the above roll form, thetoilet paper has an excellent cushioning property, and softness iseasily felt when the toilet paper is held in the hand as describedabove.

Hereinafter, the effect of the toilet paper according to the presentinvention will be further described with reference to Examples.

EXAMPLES

Next, for Reference Example, Examples, and Comparative Examples relatingto the toilet paper of the present invention, sensory evaluation wasperformed on “softness”, “fullness”, “thick feeling”, “tear and strengthduring use”, and “how small the paper dust amount during use is”. Thestructure of the toilet roll and the physical properties and compositionof the toilet paper according to each example are illustrated in Table 1below. Reference Example has a general fiber structure equivalent to aproduct using pulp bleached with chlorine-based bleaching agent, whichis also called a bleached product, and contains a larger amount of LBKP,which is hardwood pulp, than NBKP, which is softwood pulp. ComparativeExamples 5 and 6 are commercially available products each containingunbleached pulp. In Comparative Examples 1 to 3, the basis weight andthe paper thickness are particularly higher than those in Examples. Anembossment of each of Reference Example, Examples, and ComparativeExamples 1 to 4 had the pattern illustrated in FIG. 1.

For the sensory evaluation, 18 subjects actually used the rolled toiletpaper according to each example, and performed relative evaluation oneach item of “softness”, “fullness”, “thick feeling”, “tear and strengthduring use”, and “how small the paper dust amount during use is” basedon Comparative Example 6 (conventional product). In the evaluation,Comparative Example 3 was evaluated as 4 points (median), and scoringwas performed from 7 points for a good evaluation to 1 point for a poorevaluation with a difference for one point up or down, and an averagevalue thereof was calculated for judgement.

TABLE 1 Reference Comparative Comparative Comparative ComparativeComparative Comparative Comparative Example Example 1 Example 2 Example1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7Bleached/Unbleached Bleached Unbleached Unbleached Unbleached UnbleachedUnbleached Unbleached Unbleached Unbleached Unbleached Pulp NUKP % 0 0 00 0 0 0 — — — NOKP 0 100 100 100 100 100 100 — — — NBKP 35 0 0 0 0 0 0 —— — LUKP 0 0 0 0 0 0 0 — — — LOKP 0 0 0 0 0 0 0 — — — LBKP 65 0 0 0 0 00 — — — Freeness 430 cc 640 cc 640 cc Unbeaten Unbeaten UnbeatenUnbeaten — — — Softener Fatty acid-based kg/T 0.85 0.85 0.85 1.4 1.4 1.41.4 — — — softener Softening kg/T 0.5 0.5 0.5 0.5 0.5 0.5 0.5 — — —moisturizer Crepe ratio % 20 18 18 20 20 20 20 — — — Basis weight g/m²15.0 11.0 12.0 15.0 12.9 15.0 15.6 15.4 15.5 15.1 Paper thickness Singleply μm 100 86 91 138 135 135 142 92 105 96 Total plies μm 400 343 364553 540 405 365 367 315 287 Number of plies Sheet 4 4 4 4 4 3 3 4 3 3Dry tensile strength MD cN/25 mm 720 767 897 739 477 565 758 763 5791397 Dry tensile strength CD cN/25 mm 320 261 298 376 243 305 386 393461 364 Softness cN/100 mm 2.1 2.6 3.2 2.6 1.9 2.2 2.7 3.6 3.5 4.9 MMD1/100 7.0 9.5 9.5 9.1 9.0 9.0 8.8 12.1 13.5 15.3 Water-disintegrabilitySecond 17 8.5 8.5 8 8 8 8 108 49 Unmeasurable (large) Winding length m23.0 26 26 23.0 23.0 30.6 30.6 24.0 22.9 32.0 Winding diameter mm 117117 117 116 117 117 117 104 95 104 Paper tube diameter Outer diameter mm41 41 41 41 41 41 41 43 45 40 Winding density m/cm² 0.24 0.27 0.28 0.250.24 0.24 0.24 0.34 0.31 0.33 Roll density g/cm³ 0.146 0.121 0.133 0.1490.126 0.146 0.152 0.210 0.194 0.200 Roll width mm 104 104 104 103 104104 104 108 95 102 Perforation pitch mm 114 114 114 116 117 114 114 130105 110 Embossment — Present Present Present Present Present PresentPresent Absent Absent Absent Winding tightness 0.5-50 gf/cm2 mm 1.602.60 2.22 2.11 2.06 2.12 2.12 0.64 0.54 0.52 (roll) WC (Compression gf ·cm/cm2 3.16 5.25 4.49 4.23 4.39 4.19 4.29 1.09 0.96 0.97 work amount)Softness 1 to 7 6.3 6.7 6.5 6.2 6.4 6.4 6.1 4.2 4.0 4.4 Fullness 1 to 75.1 6.6 6.5 5.0 5.3 5.1 5.0 3.9 4.0 4.0 Thick feeling 1 to 7 4.9 4.5 4.56.8 6.6 4.9 4.3 4.3 4.0 3.7 Tear and strength during use 1 to 7 6.2 5.85.9 6.7 6.1 6.1 6.4 3.7 4.0 3.7 How small paper dust 1 to 7 4.7 4.5 4.52.9 3.5 3.4 3.0 4.0 4.0 3.5 amount during use is

Examples of the present invention show much better sensory evaluationresults than Comparative Examples 5 to 7, which are conventionalunbleached products, in “softness”, “fullness”, “thick feeling”, “tearand strength during use”, and “how small the paper dust amount duringuse is”. In addition, Examples of the present invention show sensoryevaluation results equivalent to or higher than the bleached product(Reference Example) in “softness”, “fullness”, “thick feeling”, “tearand strength during use”, and “how small the paper dust amount duringuse is”. That is, each of Examples of the present invention usessoftwood pulp having a long fiber length as 100% by mass raw materialpulp, and has high freeness, but obtained sensory evaluation resultsequivalent to or higher than the bleached product (Reference Example)using a papermaking raw material containing a large amount of LBKP witha short fiber length and having a low freeness. That is, each ofExamples of the present invention has quality equivalent to the bleachedproduct (Reference Example) while providing a security feeling providedby the unbleached product.

Furthermore, when Example 1 is compared with Comparative Examples 1 to4, it is evaluated that paper dust is much less likely to be generatedin Example 1.

In the form of the toilet roll, in Examples of the present invention,the compression work amount was larger than those in Reference Exampleand Comparative Examples, and more softness was felt when the toiletpaper in the roll form was held in the hand.

As described above, the toilet paper according to the present inventionprovides a thick feeling that can make a user reassured during usethereof in a shower toilet, has sufficient softness, does not easilygenerate paper dust, has excellent water-disintegrability, and providesa security feeling to a human body during use thereof.

REFERENCE SIGNS LIST

-   1 Toilet roll-   10 Toilet paper-   20 Paper tube (tube core)-   L1 Winding diameter (diameter) of toilet roll-   L2 Diameter of tube core of toilet roll-   L3 Width of toilet roll-   31, 32 Concave-   33 Valley line portion

1. A 3-ply or 4-ply toilet paper, comprising: oxygen-pulped andnon-chlorine-bleached softwood kraft pulp in an amount of 50 to 100% bymass of fibers; and a cationic fatty acid amide-based softener, whereineach ply has a basis weight of 10.5 to 12.5 g/m² and a thickness of 80to 100 μm, and the toilet paper has an overall thickness of 320 to 400μm and a water-disintegrability of 10 seconds or less.